I can't figure this out so looking for some ideas. My passenger headlight has less Lux output than the driver's side. It's quite noticable when I point at a wall. I've switched bulbs left to right, and ever tried new bulbs... The dim side stays on the passenger side. It's the same when I put Halogen bulbs back in. I've tightened every ground bolt I can see under the hood, and tested voltage on the dim side and got 11.9 volts. I'm at a loss. it's like the right side is is DRL mode and the left isn't. I'm under warranty, but not sure they'll like all the R&R ive done with the housing, or the LED bulbs... Any help would be so appreciated.

 

How many volts did you get on the bright side when you tested it? The dim side at 11.9 volts is low...especially if the truck was running when you tested it.
My hunch is that you have a lower voltage on the dim side, unless your reflector or lens is oxidized only on that side for some reason.

 

Thank you for your reply.

 

Check grounds too. GM vehicles, especially their trucks, were famous for having one headlight that worked better then the other. In their case, it usually had something to do with the grounds.

 

Check the connections for burnt terminals. We have a fleet of E 450 shuttle busses, with DRL's at work, and they will come in with one headlight dimmer than the other, and we usually find the plug for the headlight bulb, has a burnt plug.